BULLETIN OF MARINE SCIENCE 51(3) 337-352 1992

AGE GROWTH AND REPRODUCTION OF GAGMYCTEROPERCA MICROLEPIS (PISCES SERRANIDAE)

IN THE EASTERN GULF OF MEXICO

Peter B Hood and Rodric A Schlieder

ABSTRACT

A total of 1331 gag Mycteroperca microlepis captured in the eastern GulfofMexico fromNovember 1977 to May 1980 were sampled for life history analysis Gag captured in watersless than 30 m deep by commercial and nearshore recreational fishermen were significantlysmaller (TL ~ 739 mm) than those captured in greater depths (TL ~ 832 mm) Analyses ofmarginal increments annulus spacing and the relationship of otolith size to fish lengthsuggested that a ring forms on the sagittae once each year during the summer Growth of gagwas greatest during the first 10 years after which mean size approached an apparent maximumof about I 100 mm TL Estimates of the von BertalanflY growth equation parameters (standarderror) for gag were as follows L= = 1190 mm TL (22 mm) K = 0166 (0009) and to =-062 (013) Growth rate estimates determined from monthly length-frequency data forjuveniles and from historical tagging data for adults agreed with the estimate determined byanalyzing otolith sections Gag are protogynous hermaphrodites and females in the sampleoutnumbered males 6 I Females became mature between ages III and VI and no males lessthan age V were observed Histological and gravimetric analyses of gonad condition suggestedthat gag spawn from December to May with peak activity occurring during February andMarch

The gag Mycteroperca microlepis is a demersal serranid that ranges from NewYork to Rio de Janeiro excluding the West Indies (Briggs 1958 Smith 1971)Along the United States Atlantic coast and in the Gulf of Mexico gagare associa tedwith inshore-reef and shelf-break habitats (Smith et aI 1975 Huntsman 1976Huntsman and Dixon 1976) Along the west coast of Florida gagare an importantpart of the groupersnapper fishery recent landings of gag by the commercial andrecreational fisheries during 1986-1988 have totaled over 2154880 kg 1

Studies conducted in the South Atlantic Bight report that gag are long-livedslow-growing fish that may live more than 20 years (Collins et aI 1987) and maygrow to total lengths measuring over 1200 mm (Manooch and Haimovici 1978)McErlean and Smith (1964) proposed that gag are protogynous hermaphroditesbased on the remains of the ovarian lumen and lamellae and on the degeneratingoocytes in newly transformed males Furthermore they observed no females overage X and no males under age XIII Females in the South Atlantic Bight reachmaturity by age V and no males younger than age V were observed (Collins etaI 1987) In both the South Atlantic Bight and Rorida waters gag spawn fromlate winter to early spring (McErlean 1963 Collins et aI 1987)

Concern about the decreasing abundance of grouper stocks in the eastern Gulfof Mexico during the past two decades has prompted research into the life historyof these important species The objective of this paper is to describe the agegrowth and reproduction of gag captured off the coast of west central Rorida

I Combined landings data from Marine Recreational Fishery Statistics Survey National Marine Fisheries Service Silver SpringsMaryland 20910 and Annual landings Summary Marine Fisheries Information System Rorida Depanment of Natural Resources SIPetersburg Rorida 33701

337

338 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

MATERIALS AND METHODS

Gag were obtained from the commercial and recreational hook-and-Iine fisheries based in PinellasCounty Florida from November 1977 to May 1980 Most of the fish were captured in the easternGu]f of Mexico between 27deg30N and 28deg40N latitudes at depths ranging from 36 to 180 m Fishwere also collected (using seines pushnets hook and line traps and spearguns) from nearshore reefslaquo 15 m deep) west of Tampa Bay and from estuarine locations within Tampa Bay

Each month approximately 30 fish representing the entire size range captured were measured (mmTL and mm SL) and weighed (g) Sagittae were removed from the otic capsule and stored in glycerolGonads were removed fixed with Davidsons solution for approximately 24 h stored in 95 ethanoland then weighed to the nearest 00 I g Length data were stratified at 10-m depth zones and comparedusing analysis of variance and Tukeys studentized range test for pairwise comparisons (SAS InstituteInc 1985) The relationships between SL and TL and weight with SL and TL were determined byleast-squares regression analysis (SAS Institute Inc 1985)

Thin sections of sagittae were used for age determination The left otolith was sectioned throughthe core at 05-mm intervals along a transverse dorso-ventral plane using a Buehler Isomet low-speedsaw with a diamond blade Mounted sections were placed on a black field illuminated with reflectedlight and examined under a binocular dissecting microscope at 12 x magnification The magnifiedimage of the sectioned otolith was analyzed using a video image analysis system (OPRS Biosonics1987) The number of opaque bands (rings) and the measurements of the distances from the core tothe ventral edge of the otolith and from the core to the distal edge of each opaque zone were recordedInitially sections from 50 otoliths were read by two investigators to determine the reproducibility ofring counts The readers agreed on the number of rings in 38 sections (76) Because only two of the12 remaining counts differed by more than one ring one reader examined all otolith sections for agedetermination An otolith section was used for age and growth analysis only if two of three separatereadings were the same and if the greatest difference between dissimilar readings was only one ring

Validation of annulus periodicity was determined by analyzing the monthly mean marginal incre-ments and the consistency of the distance from the otolith core to each ring Monthly mean marginalincrements were compared using the Kruskal- Wallis non-parametric analysis of variance (Sokal andRohlf 1981) and frequency distributions of sequential ring location within otoliths for each age classwere constructed Monthly mean percent marginal increments [(margin a] incrementdistance betweenlast two annuli) x 100 Hood et aI in prep] and monthly mean standardized marginal increments(marginal incrementlargest marginal increment recorded for the age class Collins et aI 1987) werealso computed However the results of these analyses did not enhance the interpretation of annulusperiodicity over monthly mean marginal increments Therefore only monthly mean marginal incre-ments are presented here The relationship between otolith radius and length was determined by ]east-squares regression analysis (SAS Institute Inc 1985)

A gags length at the time the last annulus was formed was calculated from a regression of totallength on otolith radius (Ricker 1973 Bagcnal and Tesch 1981) Regressions were run on untrans-formed and log-transformed data and the regression with the best fit was selected for these calculationsLengths at the time oflast annulus formation were used to estimate the parameters ofa von Bertalanffygrowth curve using the Marquardt algorithm for calculating a non-linear regression (SAS InstituteInc 1985) Seine collections made in Tampa Bay from 1958 to 1981 provided additional length-frequency data for early growth

To examine the reproductive biology of gag a portion of each preserved gonad was embedded inparaffin thin-sectioned at 50 Ilm stained with Harris hematoxylin and counter-stained with eosin(Humason 1972) Sections were examined under a compound microscope to determine sex and gonad-development state We used gonad classes originally devised by Moe (1969) to describe gonad de-velopment in the red grouper (Epinephelus morio) Gonad classes were examined by age length andmonth The reproductive state of gag was further examined by calcu]ating a gonosomatic index foreach fish (gonad weightmiddot IOOwhole weight) and comparing monthly means After sex was determinedwe used the Wilcoxon two-sample test (Sakal and Rohlf 1981) to compare the mean length of femalesat age to the mean length of males

RESULTS

A total of 1331 gag ranging from 17 to 1222 mm in length2 were examinedduring this study (Fig 1) Tampa Bay collections included juveniles ranging froml7 to 360 mm in length (Fig 1A) whereas nearshore collections included both

Unless stated otherwise lengths are reported as total length

tSO

tOO

50

A

HOOD AND SCHLIEDER GAG LIFE HISTORY

N = 365

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to

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c N = 850SO

40

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20 IIIto bull

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o 100 200 JOG 400 SOO 100 700 800 100 1000 1100 1200

TOTAL LENGTH (mm)Figure 1 Size distribution of gag collected from the following A) Tampa Bay by seine B) nearshorereefs off Tampa Bay by seines pushnets hook and line traps and speargun and C) the commercialand rccreational hook-and-Iine catch

340 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table I Least squares linear regression equations for standard length (SL) on total length (TL) totallength on standard length and whole weight (WT) on total length and on standard length for gag takenfrom the eastern Gulf of Mexico (N = 802)

Least Squares Equation

SL = 0870(TL) - 24741TL = 1147(SL) + 30299

logoWT = 3059 (logIOTL) - 5089logoWT = 2958 (logoSL) - 4569

r

0998099809820983

juveniles and adults ranging from 20 to 1000 mm (Fig 1B) Lengths of gagcollected from the commercial and recreational fisheries ranged from 257 to 1222mm (Fig IC) Regressions of SL on TL and SL on weight resulting from thesedata are shown in Table 1

The mean size of gag captured by the commercial and recreational fisheriesincreased with increasing depth (Anova P lt 000 1) Mean lengths ranged from499 mm at IO-m depths to 995 mm at 80-m depths (Table 2) Although meansize generally increased from 10- to 80-m depths pairwise comparisons showedthat only gag captured at 10- to 30-m depths were significantly smaller (P lt 005)than gag captured at greater depths (Table 2)

Otoliths were examined from 978 gag ranging from 202 to 1222 mm in lengthThe number of opaque bands present in the otoliths ranged from 0-21 howeveraccurate measurements could only be recorded in otoliths with up to 17 bandsSixty-five of the otoliths (67) were illegible and in III otoliths (114) bandscould be counted but no measurements could be recorded because sections werebroken otoliths were oddly shaped or cores were missed in the sectioning processConsequently age and growth data were derived from only the readable portionof the sample (802 fish 819) The largest fish examined (1222 mm) had 17bands

Validation of the periodic band deposition was difficult because little variationwas observed between monthly mean marginal increments for most age groups(Fig 2) Of the 10 age groups examined only gag with three rings (Age Ill) showeda significant difference between monthly mean marginal increments (Kruskal-Wallis nonparametric analysis of variance P lt 001) However for all classes

Table 2 Mean length (mm) standard error (SE) and number of gag (N 2 12) collected from differentdepths (m) off west central Florida A multiple comparison of mean lengths by depth using Tukeysstudentized range test yielded three groups (A-C) where mean lengths assigned the same letter are notsignificantly different from each other

GroupDepth

A B C Length SE N (01)

A B 902 28 12 170A B 828 30 IS 110

B 995 22 32 80A B 895 13 140 70

B 920 13 152 60A B 876 23 64 50A B 832 14 III 40A B C 739 21 30 30A C 639 13 104 20

C 499 23 38 10

HOOD AND SCHLIEDER GAG LIFE HISTORY 341

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342 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

~ ~~~ ~ ~ __ ~ ___14bullbull~~~~ bullbullbullbull

ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

=L20

o I I I I~middot~-middot-~~~~~------------middot-~~~~~-ow0)I-04o0WCD~)Z-J

~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

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0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

338 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

MATERIALS AND METHODS

Gag were obtained from the commercial and recreational hook-and-Iine fisheries based in PinellasCounty Florida from November 1977 to May 1980 Most of the fish were captured in the easternGu]f of Mexico between 27deg30N and 28deg40N latitudes at depths ranging from 36 to 180 m Fishwere also collected (using seines pushnets hook and line traps and spearguns) from nearshore reefslaquo 15 m deep) west of Tampa Bay and from estuarine locations within Tampa Bay

Each month approximately 30 fish representing the entire size range captured were measured (mmTL and mm SL) and weighed (g) Sagittae were removed from the otic capsule and stored in glycerolGonads were removed fixed with Davidsons solution for approximately 24 h stored in 95 ethanoland then weighed to the nearest 00 I g Length data were stratified at 10-m depth zones and comparedusing analysis of variance and Tukeys studentized range test for pairwise comparisons (SAS InstituteInc 1985) The relationships between SL and TL and weight with SL and TL were determined byleast-squares regression analysis (SAS Institute Inc 1985)

Thin sections of sagittae were used for age determination The left otolith was sectioned throughthe core at 05-mm intervals along a transverse dorso-ventral plane using a Buehler Isomet low-speedsaw with a diamond blade Mounted sections were placed on a black field illuminated with reflectedlight and examined under a binocular dissecting microscope at 12 x magnification The magnifiedimage of the sectioned otolith was analyzed using a video image analysis system (OPRS Biosonics1987) The number of opaque bands (rings) and the measurements of the distances from the core tothe ventral edge of the otolith and from the core to the distal edge of each opaque zone were recordedInitially sections from 50 otoliths were read by two investigators to determine the reproducibility ofring counts The readers agreed on the number of rings in 38 sections (76) Because only two of the12 remaining counts differed by more than one ring one reader examined all otolith sections for agedetermination An otolith section was used for age and growth analysis only if two of three separatereadings were the same and if the greatest difference between dissimilar readings was only one ring

Validation of annulus periodicity was determined by analyzing the monthly mean marginal incre-ments and the consistency of the distance from the otolith core to each ring Monthly mean marginalincrements were compared using the Kruskal- Wallis non-parametric analysis of variance (Sokal andRohlf 1981) and frequency distributions of sequential ring location within otoliths for each age classwere constructed Monthly mean percent marginal increments [(margin a] incrementdistance betweenlast two annuli) x 100 Hood et aI in prep] and monthly mean standardized marginal increments(marginal incrementlargest marginal increment recorded for the age class Collins et aI 1987) werealso computed However the results of these analyses did not enhance the interpretation of annulusperiodicity over monthly mean marginal increments Therefore only monthly mean marginal incre-ments are presented here The relationship between otolith radius and length was determined by ]east-squares regression analysis (SAS Institute Inc 1985)

A gags length at the time the last annulus was formed was calculated from a regression of totallength on otolith radius (Ricker 1973 Bagcnal and Tesch 1981) Regressions were run on untrans-formed and log-transformed data and the regression with the best fit was selected for these calculationsLengths at the time oflast annulus formation were used to estimate the parameters ofa von Bertalanffygrowth curve using the Marquardt algorithm for calculating a non-linear regression (SAS InstituteInc 1985) Seine collections made in Tampa Bay from 1958 to 1981 provided additional length-frequency data for early growth

To examine the reproductive biology of gag a portion of each preserved gonad was embedded inparaffin thin-sectioned at 50 Ilm stained with Harris hematoxylin and counter-stained with eosin(Humason 1972) Sections were examined under a compound microscope to determine sex and gonad-development state We used gonad classes originally devised by Moe (1969) to describe gonad de-velopment in the red grouper (Epinephelus morio) Gonad classes were examined by age length andmonth The reproductive state of gag was further examined by calcu]ating a gonosomatic index foreach fish (gonad weightmiddot IOOwhole weight) and comparing monthly means After sex was determinedwe used the Wilcoxon two-sample test (Sakal and Rohlf 1981) to compare the mean length of femalesat age to the mean length of males

RESULTS

A total of 1331 gag ranging from 17 to 1222 mm in length2 were examinedduring this study (Fig 1) Tampa Bay collections included juveniles ranging froml7 to 360 mm in length (Fig 1A) whereas nearshore collections included both

Unless stated otherwise lengths are reported as total length

tSO

tOO

50

A

HOOD AND SCHLIEDER GAG LIFE HISTORY

N = 365

339

-0middot ---------bull----------------------------------------bullbull~bullbull~bullbull

tS B N-116

to

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c N = 850SO

40

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20 IIIto bull

0- ----------~ ~ - ii bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull bullbullbullbullbullbullbullbull ~

o 100 200 JOG 400 SOO 100 700 800 100 1000 1100 1200

TOTAL LENGTH (mm)Figure 1 Size distribution of gag collected from the following A) Tampa Bay by seine B) nearshorereefs off Tampa Bay by seines pushnets hook and line traps and speargun and C) the commercialand rccreational hook-and-Iine catch

340 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table I Least squares linear regression equations for standard length (SL) on total length (TL) totallength on standard length and whole weight (WT) on total length and on standard length for gag takenfrom the eastern Gulf of Mexico (N = 802)

Least Squares Equation

SL = 0870(TL) - 24741TL = 1147(SL) + 30299

logoWT = 3059 (logIOTL) - 5089logoWT = 2958 (logoSL) - 4569

r

0998099809820983

juveniles and adults ranging from 20 to 1000 mm (Fig 1B) Lengths of gagcollected from the commercial and recreational fisheries ranged from 257 to 1222mm (Fig IC) Regressions of SL on TL and SL on weight resulting from thesedata are shown in Table 1

The mean size of gag captured by the commercial and recreational fisheriesincreased with increasing depth (Anova P lt 000 1) Mean lengths ranged from499 mm at IO-m depths to 995 mm at 80-m depths (Table 2) Although meansize generally increased from 10- to 80-m depths pairwise comparisons showedthat only gag captured at 10- to 30-m depths were significantly smaller (P lt 005)than gag captured at greater depths (Table 2)

Otoliths were examined from 978 gag ranging from 202 to 1222 mm in lengthThe number of opaque bands present in the otoliths ranged from 0-21 howeveraccurate measurements could only be recorded in otoliths with up to 17 bandsSixty-five of the otoliths (67) were illegible and in III otoliths (114) bandscould be counted but no measurements could be recorded because sections werebroken otoliths were oddly shaped or cores were missed in the sectioning processConsequently age and growth data were derived from only the readable portionof the sample (802 fish 819) The largest fish examined (1222 mm) had 17bands

Validation of the periodic band deposition was difficult because little variationwas observed between monthly mean marginal increments for most age groups(Fig 2) Of the 10 age groups examined only gag with three rings (Age Ill) showeda significant difference between monthly mean marginal increments (Kruskal-Wallis nonparametric analysis of variance P lt 001) However for all classes

Table 2 Mean length (mm) standard error (SE) and number of gag (N 2 12) collected from differentdepths (m) off west central Florida A multiple comparison of mean lengths by depth using Tukeysstudentized range test yielded three groups (A-C) where mean lengths assigned the same letter are notsignificantly different from each other

GroupDepth

A B C Length SE N (01)

A B 902 28 12 170A B 828 30 IS 110

B 995 22 32 80A B 895 13 140 70

B 920 13 152 60A B 876 23 64 50A B 832 14 III 40A B C 739 21 30 30A C 639 13 104 20

C 499 23 38 10

HOOD AND SCHLIEDER GAG LIFE HISTORY 341

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342 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

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ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

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~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

tSO

tOO

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TOTAL LENGTH (mm)Figure 1 Size distribution of gag collected from the following A) Tampa Bay by seine B) nearshorereefs off Tampa Bay by seines pushnets hook and line traps and speargun and C) the commercialand rccreational hook-and-Iine catch

340 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table I Least squares linear regression equations for standard length (SL) on total length (TL) totallength on standard length and whole weight (WT) on total length and on standard length for gag takenfrom the eastern Gulf of Mexico (N = 802)

Least Squares Equation

SL = 0870(TL) - 24741TL = 1147(SL) + 30299

logoWT = 3059 (logIOTL) - 5089logoWT = 2958 (logoSL) - 4569

r

0998099809820983

juveniles and adults ranging from 20 to 1000 mm (Fig 1B) Lengths of gagcollected from the commercial and recreational fisheries ranged from 257 to 1222mm (Fig IC) Regressions of SL on TL and SL on weight resulting from thesedata are shown in Table 1

The mean size of gag captured by the commercial and recreational fisheriesincreased with increasing depth (Anova P lt 000 1) Mean lengths ranged from499 mm at IO-m depths to 995 mm at 80-m depths (Table 2) Although meansize generally increased from 10- to 80-m depths pairwise comparisons showedthat only gag captured at 10- to 30-m depths were significantly smaller (P lt 005)than gag captured at greater depths (Table 2)

Otoliths were examined from 978 gag ranging from 202 to 1222 mm in lengthThe number of opaque bands present in the otoliths ranged from 0-21 howeveraccurate measurements could only be recorded in otoliths with up to 17 bandsSixty-five of the otoliths (67) were illegible and in III otoliths (114) bandscould be counted but no measurements could be recorded because sections werebroken otoliths were oddly shaped or cores were missed in the sectioning processConsequently age and growth data were derived from only the readable portionof the sample (802 fish 819) The largest fish examined (1222 mm) had 17bands

Validation of the periodic band deposition was difficult because little variationwas observed between monthly mean marginal increments for most age groups(Fig 2) Of the 10 age groups examined only gag with three rings (Age Ill) showeda significant difference between monthly mean marginal increments (Kruskal-Wallis nonparametric analysis of variance P lt 001) However for all classes

Table 2 Mean length (mm) standard error (SE) and number of gag (N 2 12) collected from differentdepths (m) off west central Florida A multiple comparison of mean lengths by depth using Tukeysstudentized range test yielded three groups (A-C) where mean lengths assigned the same letter are notsignificantly different from each other

GroupDepth

A B C Length SE N (01)

A B 902 28 12 170A B 828 30 IS 110

B 995 22 32 80A B 895 13 140 70

B 920 13 152 60A B 876 23 64 50A B 832 14 III 40A B C 739 21 30 30A C 639 13 104 20

C 499 23 38 10

HOOD AND SCHLIEDER GAG LIFE HISTORY 341

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342 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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~ tAature Resting

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90 -80 -70 -

60 -50 -

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30 -

20 -

10 -

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90 -80 -

70 -60 -

50 -

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o Spent

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Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

340 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table I Least squares linear regression equations for standard length (SL) on total length (TL) totallength on standard length and whole weight (WT) on total length and on standard length for gag takenfrom the eastern Gulf of Mexico (N = 802)

Least Squares Equation

SL = 0870(TL) - 24741TL = 1147(SL) + 30299

logoWT = 3059 (logIOTL) - 5089logoWT = 2958 (logoSL) - 4569

r

0998099809820983

juveniles and adults ranging from 20 to 1000 mm (Fig 1B) Lengths of gagcollected from the commercial and recreational fisheries ranged from 257 to 1222mm (Fig IC) Regressions of SL on TL and SL on weight resulting from thesedata are shown in Table 1

The mean size of gag captured by the commercial and recreational fisheriesincreased with increasing depth (Anova P lt 000 1) Mean lengths ranged from499 mm at IO-m depths to 995 mm at 80-m depths (Table 2) Although meansize generally increased from 10- to 80-m depths pairwise comparisons showedthat only gag captured at 10- to 30-m depths were significantly smaller (P lt 005)than gag captured at greater depths (Table 2)

Otoliths were examined from 978 gag ranging from 202 to 1222 mm in lengthThe number of opaque bands present in the otoliths ranged from 0-21 howeveraccurate measurements could only be recorded in otoliths with up to 17 bandsSixty-five of the otoliths (67) were illegible and in III otoliths (114) bandscould be counted but no measurements could be recorded because sections werebroken otoliths were oddly shaped or cores were missed in the sectioning processConsequently age and growth data were derived from only the readable portionof the sample (802 fish 819) The largest fish examined (1222 mm) had 17bands

Validation of the periodic band deposition was difficult because little variationwas observed between monthly mean marginal increments for most age groups(Fig 2) Of the 10 age groups examined only gag with three rings (Age Ill) showeda significant difference between monthly mean marginal increments (Kruskal-Wallis nonparametric analysis of variance P lt 001) However for all classes

Table 2 Mean length (mm) standard error (SE) and number of gag (N 2 12) collected from differentdepths (m) off west central Florida A multiple comparison of mean lengths by depth using Tukeysstudentized range test yielded three groups (A-C) where mean lengths assigned the same letter are notsignificantly different from each other

GroupDepth

A B C Length SE N (01)

A B 902 28 12 170A B 828 30 IS 110

B 995 22 32 80A B 895 13 140 70

B 920 13 152 60A B 876 23 64 50A B 832 14 III 40A B C 739 21 30 30A C 639 13 104 20

C 499 23 38 10

HOOD AND SCHLIEDER GAG LIFE HISTORY 341

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342 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

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o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

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100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

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100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

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IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

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15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

HOOD AND SCHLIEDER GAG LIFE HISTORY 341

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

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~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

342 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

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90 -80 -

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Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

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~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

HOOD AND SCHLIEDER GAG LIFE HISTORY 343

examined except age IX the widest monthly mean marginal increment was ob-served between March and August which suggests that opaque band depositionis completed during this time period

Periodic band deposition is indirectly supported by 1) the consistency of ringlocation from the otolith core and 2) the positive correlation of otolith size andfish length For all age groups frequency distributions of the distance of each ringfrom the otolith core was modal and the location of these modes remainedconsistent among age classes For example the mode for the first ring remainsbetween 10 and 25 mm the second between 15 and 30 mm the third between20 and 40 mm the fourth between 25 and 45 mm etc (Fig 3) However asthe number of rings increases the modes for the fifth ring and above become lessdefined possibly due to the increased variability with time in otolith growthThe natural log of otolith radius and the natural log of fish length gave the bestfit for the regression of length on otolith radius and is described by the followingrelationship In(TL) = (1117-ln (otolith radius)) + 5146 (r2 = 0850) Despitethe inconclusive nature of our validation data evidence given by other authors(McErlean 1963 Matheson and Huntsman 1984 Matheson et aI 1986 andCollins et al 1987 1990) leads us to assume that one opaque band is formedeach year of life

Growth rates of gag were greatest through age X after which mean size ap-proached an apparent maximum of about 1100 mm (Table 3A) Age and cal-culated length data from 797 gag were fit to a von Bertalanffy growth curve andwere defined by the following parameters (standard error) Lao = 1180 mm (28mm) K = 0165 (0013) and to = -074 (0199) The fish selected for thesecalculations ranged in age from I to XVII and had mean lengths ranging from422 mm for age I to 1140 mm for age XVII Analysis of monthly length-frequencydata from gag captured in Tampa Bay showed that gag can grow to 220-340 mmby the end of their first year Juvenile gag were 17-40 mm long in April and bythe following February they were 220-340 mm long (Fig 4) The length at age Ipredicted by the von Bertalanffy growth curve (281 mm Table 3A) falls withinthis range

Overall female gag outnumbered males by approximately 6 1 (818 134) andsix transitional gag were observed However the percentage of females decreasedas size and age increased (Table 4) Fish were exclusively female at sizes less than812 mm and ages less than V however by 1050 mm and age XI males comprisedabout 50 of the sample Between ages V and XI mean lengths of males weregreater than those of females however only at ages VIII and X were malessignificantly larger (P lt 005 Table 3) After age XI mean sizes at age for malesand females were not significantly different

Females reach maturity primarily between ages III and IV and their transfor-mation into males begins as early as age V Mature females were observed at agesII-XVI (Table 4) By age IV 70 of females were mature (classified as eithermature resting mature active or spent) and 100 were mature by age VI Gonadsfrom 12 aged individuals were transforming into testes or had just transformed(immature males) These individuals ranged from age V to XIII five of the 12were ages VIII or IX

Figure 3 Frequency distributions of the distance from the otolith core to each band for age classesI to X Inverted triangles indicate mean location of each band

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

~ ~~~ ~ ~ __ ~ ___14bullbull~~~~ bullbullbullbull

ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

=L20

o I I I I~middot~-middot-~~~~~------------middot-~~~~~-ow0)I-04o0WCD~)Z-J

~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

344 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 3 Number of gag sampled mean length (standard error) and minimum and maximum lengthsfor ages O-XXI presented for (A) Sexes combined (B) Females and (C) Males Predicted length isbased on the von Bertalanffy growth curve TL = 1180middot[1 - e-o 165-(0 + 074)] = Mean length offemalessignificantly different from males of the same age

ObservedAge N Mean TL (SEl Min TL Max TL Predicted TL

A Sexes Combined0 5 322 (16) 283 361I 19 383 (17) 257 530 281II 24 476 (IS) 350 678 420III 78 592 (9) 443 785 538IV 126 695 (8) 487 910 637V 143 779 (7) 467 992 722VI 138 828 (8) 654 1110 793VII 79 896 (8) 676 1041 854VIII 63 942 (9) 802 1067 905IX 69 981 (7) 765 1085 949X 48 1024 (10) 890 1129 986XI 30 1043 (18) 642 1170 1017XII 13 1079 (9) 1030 1125 1044XIII 18 1079 (6) 1029 1123 1066XIV 13 1092 (IS) 1010 1222 1085XV 9 1088 (IS) 1008 1127 1101XVI 6 1091 (20) 1035 1165 1115XVII 3 1089 (2) 1086 1089 1126XVIII I 1130 (-) 1136XIX 0 1144XX 2 1060 (21) 1039 1080 1151XXI I 1140 (-) 1157

B Females0 5 322 (16) 283 361I 19 383 (17) 257 530II 24 476 (15) 350 678III 78 593 (9) 443 785IV 126 695 (8) 487 910V 141 778 (7) 467 980VI 135 824 (7) 654 1020VII 77 896 (9) 676 1040VIII 59 937 (9) 802 1065IX 56 976 (8) 765 1085X 27 989(13) 890 1085XI 16 1023 (31) 642 1170XII 3 1096 (7) 1085 1110XIII 5 1054 (12) 1029 1100XIV 3 1110 (20) 1082 1150XV 2 1086 (38) 1048 1124XVI 2 1081 (47) 1035 1128XVII 0XVIII 0XIX 0XX 0XXI 0

C Males0 1 992 (-)I 2 1085 (25) 1060 1110II 1 946 (-)III 4 1019 (22) 971 1067IV 13 1002 (17) 865 1085V 21 1070 (7) 1018 1129VI 14 1068 (13) 998 1150

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

~ ~~~ ~ ~ __ ~ ___14bullbull~~~~ bullbullbullbull

ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

=L20

o I I I I~middot~-middot-~~~~~------------middot-~~~~~-ow0)I-04o0WCD~)Z-J

~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

HOOD AND SCHLIEDER GAG LIFE HISTORY 345

Table 3 Continued

ObservedAge N Mean TL (SE) Min TL Max TL Predicted TL

VII 9 1075 (12) 1030 1125VIII 12 1089 (6) 1050 1123IX 10 1088 (18) 1010 1222X 7 1088 ( 7) 1008 1127XI 4 1096 (24) 1059 1165XII 3 1089 (2) 1086 1094XIII 1 1130 (-)XIV degXV 2 1059 (21) 1039 1080XVI I 1140 (-)XVII degXVIII degXIX degXX degXXI deg

Gag have a protracted spawning period that extends at least from Decemberto May Spent females were observed during this period (Fig SA) The highpercentage of mature active and spent females in February and March indicatedthat peak spawning occurred at this time Gag with ripe and spent testes weremost prevalent from November to May (Fig SB) Little spawning ifany occurredduring the summer and fall months and was evidenced by a high percentage offemales with mature resting ovaries from June through November and a highpercentage of males with mature inactive testes from June to October

These observations of a winter-spring period of active spawning and a summer-fall period of inactivity were also apparent in trends of monthly mean gonosomaticindices and collections of juvenile gag For both males and females the relativeweight of gonads increased from September to March indicating ripening (Fig6) Relative weight decreased from March to September indicating that gametesshed and that the gonads entered the spent-resting state For females dramaticincreases in relative gonad weight in February and March (131 and 183 re-spectively) indicated peak spawning Winter and spring spawning were also in-dicated by the presence of small juveniles that were captured with seines duringApril (17-36 mm) and May (18-71 mm) in Tampa Bay (Fig 4) Estimated agesof similar-sized fish from South Carolina are 40-60 and 40-80 days old respec-tively (Keener et al 1988)

DISCUSSION

The mean sizes of gag captured in the eastern Gulf of Mexico by the commercialand recreational hook-and-line fisheries increased as the depth of capture in-creased up to a depth of 80 m This increase in size with depth has also beenreported for gag by Moe (1966 1972) Huntsman and Dixon (1976) and Manoochand Haimovici (1978) and may indicate that different fishing pressures have beenexerted at different depths and thus that larger fish have been previously removedor it may indicate that gag migrate to deeper waters as they mature Keener et al(1988) reported that although young-of-the-year gag occur in high-salinity barrierisland inlets in South Carolina they are virtually absent in offshore trap collectionsJuvenile gag were also found in the estuarine waters of Tampa Bay where McErlean

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

~ ~~~ ~ ~ __ ~ ___14bullbull~~~~ bullbullbullbull

ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

=L20

o I I I I~middot~-middot-~~~~~------------middot-~~~~~-ow0)I-04o0WCD~)Z-J

~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

346 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

bull I bullbullbull

I ~

FebruaryN-4

WayN - 17t

JuneN-ilil

AUgU8tN - 24

OctoberN-II

I bull I I I

JulyN - 16

bull I bull 1 ~----_---TO

I I I bull

lLll- ~ ~~~ I September

~ ~~~ ~ ~ __ ~ ___14bullbull~~~~ bullbullbullbull

ll~~-~11 --_~~-r-r_bullbull- ___ ~~-r-r_~ bullbull ~_mbull~_er~bullbull_ ~I

2degL1010

11 ~~~

n ~~~_---r--~- ~----~_~~_12bullbullbull~~-

11----r ~- ~-------rbullbull~- bullbull_~bull-bull~bull7~-bullbullbull

=L20

o I I I I~middot~-middot-~~~~~------------middot-~~~~~-ow0)I-04o0WCD~)Z-J

~oI-

o 20 40 80 110 100 120 140 110 1110 200 220 240 210 210 JOG 320 340 310

TOTAL LENGTH (mm)Figure 4 Monthly length-frequency distributions of larval and juvenile gag collected in the TampaBay estuary from June 1958 to June 1981

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

HOOD AND SCHLIEDER GAG LIFE HISTORY 347

Table 4 Number and percentage of gag by stage of sexual maturity for A) total length (TL) and B)age IMF = immature female MF = mature female (mature resting mature active spent)MF = percentage of mature females for females combined T = transitional IMM = immature malesMM = mature males (mature inactive ripening mature ripe spent) and F = overall percentage offemales Transitional fish were not used to calculate either MF or F

TLMidpoint IMF MF MF T IMM MM F

A350 6 0 0 0 0 0 100400 10 0 0 0 0 0 100450 14 2 13 0 0 0 100500 19 5 21 0 0 0 100550 21 6 22 0 0 0 100600 29 21 42 0 0 0 100650 16 29 64 0 0 0 100700 17 59 78 0 0 0 100750 20 69 78 0 0 0 100800 7 86 92 I 0 0 100850 0 87 100 0 I 0 99900 0 98 100 I 0 0 100950 0 76 100 0 I 4 94

1000 0 64 100 2 4 IS 771050 0 37 100 I 3 39 471100 0 IS 100 I 0 54 221150 0 5 100 0 0 10 331200 0 0 0 0 0 3 0

Age IMF MF MF T IMM MM F

BI 16 0 0 0 0 0 100II 20 I 5 0 0 0 100III 52 25 32 0 0 0 100IV 38 88 70 0 0 0 100V 22 118 84 I 0 I 99VI 6 129 96 I I I 98VII 0 77 100 I 0 I 99VIII 0 59 100 0 2 2 94IX 0 56 100 0 3 10 81X 0 28 100 0 I 20 57XI 0 16 100 0 0 14 53XII 0 3 100 I 0 9 25XIII 0 5 100 I 0 13 28XIV 0 3 100 0 0 10 23XV 0 2 100 0 0 7 22XVI 0 2 100 0 0 4 33XVII 0 0 0 0 3 0XVIII 0 0 0 0 I 0XIX 0 0 0 0 0XX 0 0 0 0 2 0XXI 0 0 0 0 I 0

(1963) reported them abundant in the bycatch of the bait shrimp fishery Thisobservation led Moe (1966) to suggest that juvenile gag may migrate offshorefrom estuarine areas Tagging studies indicate that adult gag show residencespecificity to reefs (Moe 1966 Beaumariage 1969) therefore after juvenilesleave estuarine waters for deeper waters they become site specific The degree ofthis site specificity is unknown Collins et al (1990) tagged several large gag (75cm TL) that traveled from reefs off Charleston Sc to southern florida They

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

348 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

A Female

DSpent

esJ tAature Active

~ tAature Resting

IIImmature

~J-I ~11- ~amplt ~amplt ~amplt ~amplt~~o amp~ oc-o Namp~ Ce~

amp~ ~o ~e

Month

100 -

90 -80 -70 -

60 -50 -

40 -

30 -

20 -

10 -

0-0lt1 0lt1 ~c~bullo~~ ~o-l ~(-e

~v ~v ~~ rlt oJ~~ ltt0Q

-+-cQ)ULQ)

0

B Male

-+-cQ)ULQ)

0

100 -

90 -80 -

70 -60 -

50 -

40 -

30 -

20 -10 -

0-voltl ~o( ofc~~~~ 0-1 ~~(-amp

~o~ltt0Qf ~

o Spent

l2J Ripe

~ Ripening tAature

~ tAature Inactive

IIImmature

Figure 5 Percent frequency of reproductive classes each month for A) females and B) males

hypothesized that at least some gag in the South Atlantic Bight may undergo aspawning migration to south Rorida Whether these gag return to their originalpoint of departure or if northeastern Gulf of Mexico gag undergo a similar mi-gration is unknown

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

2S

HOOD AND SCHLIEDER GAG LIFE HISTORY 349

lI_~ bull _

GSoz(j

~~o()ozo()

20

15

10

05

00

SOLID - FEMALEDASHED - MALE

--JAN FEB MAR APR ~y JUN JUL AUG SEP OCT NOV DEC

MONTHFigure 6 Mean gonosomatic index (plusmn I SE) plotted at monthly intervals for male and female gag

Sagittae could readily be used to determine the age of gag Approximately 95of otolith sections were legible for determining age This compares favorably withother studies that also used otoliths to age gag (Manooch and Haimovici 1978[79] Collins et al 1987 [87]) Marginal increment data suggest that opaqueband formation occurs during the spring and summer in the eastern Gulf McErlean(1963) examined whole otoliths from gag captured off the west coast of Floridaand found annuli formed from April to July Analysis of sectioned otoliths fromgag captured in the South Atlantic Bight showed that annuli were laid down inthe late spring and midsummer for gag less than age IX and in August for gaggreater than age VIII (Collins et al 1987) The regular position of correspondingbands is further evidence that the bands are deposited once a year Similar analysesof these types of data have been used for the validation of annuli periodicity inscamp (M phenax Matheson et al 1986) speckled hind (Epinephelus drum-mondhayi) and snowy grouper (E niveatus Matheson and Huntsman 1984)Direct evidence for yearly deposition of annuli in gagwas demonstrated by Collinset al (1990) using tetracycline-injected tagged fish However a true validationof band periodicity as suggested by Beamish and McFarlane (1983) for Gulf ofMexico gag is still needed

The maximum observed age of gag in the eastern Gulf (21 years) is similar tothat observed for gag in the South Atlantic Bight (22 years Collins et al 1987)These maximum ages are much greater than those observed by McErlean (1963)in the eastern Gulf and by Manooch and Haimovici (I 978) in the South AtlanticBight These authors examined whole otoliths and counted a maximum of 13annuli Our data support the contention made by Collins et al (1987) that annuliat the edge of gag otoliths are more readily observed in otolith sections than theyare in whole otoliths

Our estimates of growth yielded lengths at age which were larger than that ofMcErlean (1963) for this species along the west central Florida coast Our predicted

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

350 BULLETIN OF MARINE SCIENCE VOL 51 NO3 1992

Table 5 Actual growth of tagged gag Mycteroperca microlepis compared to growth estimated froma von BertalanffY growth curve Age at first capture is predicted from the curve Data are from Topp(1963) Beaumariage (1964)b Beaumariage and Wittich (1966) Beaumanage (1969)d and Moe (1970)

First capture

Predicted ageGrowth (mm)

Difference(yrs) Length (mm) Days at large Actual (A) Predicted (P) (A - P)

190 328 814 155 321 -166214 364d 634 223 261 -38256 425d 815 155 280 -125270 445 337 105 157 -51273 449d 322 51 151 -101284 464d 704 204 240 -36396 600d 423 90 131 -41740 890d 1130 162 III +50183 317b 488 161 238 -77218 371b 378 68 190 -122184 320b 362 110 200 -90462 670 2307 381 346 +35134 238 207 34 171 -136169 295 140 10 134 -124

bull Predicted age was calculated by estimating the von Benalantry growth parameters using the Marquardt algorithm for calculating anonmiddot linear regression on the same data (SAS Institute Inc 1985) but solving the von Bertalanffy growth equation for age instead oflength This calculation yielded the following parameters (standard error) L = 1267 mm TL (37 mm) K = 0166 (00001) andTo = 010 (0001)

lengths at age ranged from 295 mm at age I to 793 mm at age VI whereas thoseof McErlean (1963) ranged from 210 mm (191 mm SL) at age I to 720 mm (590mm SL) at age VI The reason for this discrepancy is unknown however ourobserved empirical growth rate (Table 3A) was very close to that reported byCollins et al (1987) for gag from the South Atlantic Bight 347 mm for age I 824mm for age VI and 1125 mm for age XXI Growth data from tagging studies inthe eastern Gulf showed a slower growth rate than that estimated in our studyUsing length data for 15 fish from studies by Topp (1963) Beaumariage (19641969) Beaumariage and Wittich (1966) and Moe (1970) actual growth wascompared to predicted growth employing the von Bertalanffy growth curve cal-culated in this study (Table 5) Our curve generally over-estimated the observedgrowth of 13 of 15 tagged fish

Our estimates of growth-curve parameters are the only estimates available forgag in the eastern Gulf of Mexico Com pari ng von Bertalanffy growth parameterscalculated by Manooch and Haimovici (1978) for gag captured in the SouthAtlantic Bight (Loo= 1290 mm TL K = 012154 and to = -1l27) to theseparameters calculated in our study predicted sizes at age would be 1) similar atage I 2) smaller in the southeast Atlantic at ages II-XII and 3) larger in thesoutheast Atlantic at ages above XII Our estimated parameters are within theranges for serranids given by Manooch (1987) ie a maximum age over 10 yearsand K between 010 and 025

The overall sex ratio of fish collected in the eastern Gulf was overwhelminglyfemale with a low incidence of fish in transition McErlean and Smith (1964)examined histological preparations of 32 gag gonads and females outnumberedmales by 151 Collins et al (1987) also examined gag gonads histologically andfound an overall sex ratio of about 6 1 We observed few transitional gonads inour study (1l) Collins et al (1987) also found a low percentage (125) andhypothesized that sexual transformation occurs rapidly ie few individuals arefound in this stage Roberts and Schlieder (1983) artificially induced sexual trans-

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

HOOD AND SCHLIEDER GAG LIFE HISTORY 351

formation in gag using orally administered testosterone and found gonad reversalto occur within 150 days

Female gag mature as early as ages II-III in the eastern Gulf of Mexico whichis similar to the observed age at maturity for gag in the South Atlantic Bight(Collins et al 1987) McErlean and Smith (1964) estimated that gag femalesmature around their fifth or sixth year however they looked at only 32 gag onlyfour of which were age IV and none of which were age III McErlean and Smith(1964) estimated that females transform to males during their tenth or eleventhyear We and Collins et al (1987) found that sexual transformation can occur asearly as age V and we observed the highest frequency of transforming individualsbetween ages VIII and IX

The mean size of females from ages V to IX was less than that observed formales This difference suggests that at these ages the largest females transform tomales or that once sexual transformation is complete the rate of growth increasesrapidly Because the sizes of males and females are comparable at ages greaterthan X the first interpretation appears more likely

Gag spawn from November to May with peak activity occurring in Februaryand March in the eastern Gulf McErlean (1963) also found that gag sampled offwest central Florida spawned during the winter and spring with peak spawningactivity occurring from January to March Peak spawning of gag from the SouthAtlantic Bight occurs later in the year from late March to early April (Collins etal 1987 Keener et al 1988)

Gag fit the generalized model for serranid growth and reproduction they arelong-lived slow-growing protogynous hermaphrodites (Manooch 1987 Shapiro1987) Manooch and Haimovici (1978) warn that the gag may be susceptible toover-harvesting because it grows slowly is a top-level carnivore and is habitat-specific Furthermore protogynous hermaphroditism results in an unequal sexratio in which there are fewer older and larger males This inequality may resultin differential fishing mortality for the two sexes (Shapiro 1987) These factorsneed to be considered when developing management strategies for this species

ACKNOWLEDGMENTS

We thank M F Godcharles and L H Bullock for assistance in the field K J Peters and M MLeiby for use of their larval and juvenile gag data J E Williams for histological preparations EMcManus for his diligence at the otolith saw and J 1 Kimmel J Leiby B Mahmoudi R E MathesonM D Murphy K J Peters R G Taylor and two anonymous reviewers for their help in reviewingthis paper This study was funded in part by the US Department of Commerce National Oceano-graphic Atmospheric Administration National Marine Fisheries Service under PL 88-309 ProjectNo 2-341-R and PL 99-659 Project 2-11-2

LITERATURE CITED

Bagenal T B and F W Tesch 1981 Age and growth Pages 101-136 in T B Bagenal ed Methodsfor assessment of fish production in fresh waters Blackwell Scientific Publications Oxford

Beamish R J and G A McFarlane 1983 The forgotten requirement for age validation in fisheriesbiology Trans Am Fish Soc 112 735-743

Beaumariage D S 1964 Returns from the 1963 Schlitz tagging program Fla Bd Conserv MarLab Tech Ser No 43 34 pp

-- 1969 Returns from the 1965 Schlitz tagging program including a cumulative analysis ofprevious results Fla Bd Conserv Mar Lab Tech Ser No 59 38 pp

-- and A C Wittich 1966 Returns from the 1964 Schlitz tagging program Fla Bd ConservMar Lab Tech Ser No 47 50 pp

Biosonics 1987 Optical pattern recognition system Biosonics Inc Seattle Washington 139 ppBriggs J C 1958 A list of Florida fishes and their distribution Bull Fla State Mus BioI Ser 2

223-318

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

Matheson R H and G R Huntsman 1984 Growth mortality and yield-per-recruit models forthe speckled hind and snowy-grouper from the United States South Atlantic Bight Trans AmFish Soc 113 607-616

--- --- and C S Manooch 1986 Age growth mortality food and reproduction of thescamp Mycteroperca phenax collected off North Carolina and South Carolina Bull Mar Sci38 300-312

McErlean A J 1963 A study of the age and growth of the gag Mycteroperca microlepis Goodeand Bean (Pisces Serranidae) on the west coast of Florida Fla Bd Conserv Mar Lab TechSer No 41 29 pp

--- and C L Smith 1964 The age of sexual succession in the protogynous hermaphroditeMycteroperca microlepis Trans Am Fish Soc 93 301-302

Moe M A 1966 Tagging fishes in Florida offshore waters Fla Bd Conserv Mar Lab Tech SerNo 49 40 pp

--- 1969 Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulfof Mexico Fla Dep Nat Resour Mar Res Lab Prof Pap Ser 10 95 pp

--- 1970 Return of tagged gag Mycteroperca microlepis and Caribbean red snapper Lutjanuscampechanus after six years of freedom Trans Am Fish Soc 99 428-429

--- 1972 Movement and migration of south Florida fishes Fla Bd Conserv Mar Lab TechSer No 69 25 pp

Ricker W E 1973 Linear regressions in fishery research J Fish Res Bd Can 30 409-434Roberts D E and R A Schlieder 1983 Induced sex inversion maturation spawning and em-

bryogeny of the protogynous grouper Mycteroperca microlepis J World Maricult Soc 14 639-649

SAS Institute Inc 1985 SAS users guide statistics SAS Institute Inc Cary North Carolina956 pp

Shapiro D Y 1987 Reproduction in groupers Pages 295-327 in 1 J Polovina and S Ralstoneds Tropical snappers and groupers biology and fisheries management Westview Press IncBoulder and London

Smith C L 1971 A revision of the American grouper Epinephelus and allied genera Bull AmMus Nat Hist 146 71-241

Smith G B H M Austin S A Bortone R W Hastings and L H Ogren 1975 Fishes of theFlorida Middle Grounds with comments on ecology and zoogeography Fla Mar Res Publ No914 pp

Sokal R R and F 1 Rohlf 1981 Biometry W H Freeman and Co New York 859 ppTopp R 1963 The tagging of fishes in Florida 1962 program Fla State Bd Conserv Prof Pap

Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

352 BU LLETIN OF MARINE SCIENCE VOL 5 I NO3 1992

Collins M R S B Van Sant and D J Schmidt 1990 Age validation of tag-recaptured reef fishoff South Carolina Page 73 in 70th Annual Meeting of the American Society of Ichthyologistsand Herpetologists (Abstract)

--- C W Waltz W A Roumillat and D L Stubbs 1987 Contribution to the life history andreproductive biology of gag Mycteroperca microlepis (Serranidae) in the South Atlantic BightUS Natl Mar Fish Servo Fish Bull 85 648-653

Humason G L 1972 Animal tissue technique W H Freeman amp Co San Francisco California641 pp

Huntsman G R 1976 Offshore headboat fishing in North and South Carolina US Natl MarFish Servo Mar Fish Rev 33 13-23

--- and R L Dixon 1976 Recreational catches of four species of groupers in the Carolinaheadboat fishery Proc 29th Annual Conf SE Assoc Game Fish Comm 29 185-194

Keener P G D Johnson B W Stender E B Brothers and H R Beatty 1988 Ingress ofpostlarvalgag Mycteroperca microlepis (Pisces Serranidae) through a South Carolina barrier island inletBull Mar Sci 42 376-396

Manooch C S 1987 Age and growth of snappers and groupers Pages 329-373 in J J Polovinaand S Ralston eds Tropical snappers and groupers biology and fisheries management WestviewPress Inc Boulder and London

--- and M Haimovici 1978 Age and growth of the gag Mycteroperca microlepis and size-agecomposition of the recreational catch off the southeastern United States Trans Am Fish Soc107 234-240

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Ser No5 76 pp

DATEACCEPTED December 10 1991

ADDRESS Florida Marine Research Institute Department of Natural Resources 100 Eighth AvenueSE St Petersburg Florida 33701-5095

344 BULLETIN OF MAKINE SCIENCE VOL SI NO 3 IW2

Table 3 Number of gag sampled mean length (standard error) and mmimum and maximum lengths for ages 0-XXI presented for (A) Sexes combined (B) Females and (Q Males Predicted length is based on the von Bertalanffy growth curve TL - 1180-( 1 significantly different from males of the same age

- - 0 ItS-ll + 0 74raquo] ) bull - Mean length of females

a (U

r-i O u u

o u

bullH

o laquo4-1 i H

O U

sectJ VJ

(U i-y

l lt p D i to

OS 4-1 0)

o pound 4-1

c o c

bulli-t - H 4J o -D - ^ ^ (U - (0 Ij O Qlt-H (U C a (0

^

T 0)

CO

M

U o u

0)

4-) Oraquo 04

i n

I

n n

ro

in 0) o c ltuuml

bull H U

CO

(U c

bull H

o

4-) 0

S

a Eu

o

EH

a

I CO H

M

n u

Alaquoc

A Sexes Combined

0 I

n m IV V VI

vn vni DC X XI

xn XIII XIV XV XVI XVII XVIII XIX XX XXI

B Femak 0 I II

m IV V VI

vn vin IX X XI XII XIII XIV XV XVI XVII XVIII XIX XX XXI

c Maies 0 I

n ni IV V VI

N

5 19 24 78

126 143 138 79 63 69 48 30 13 18 13 9 6 3 1 0 2 1

S 19 24 78

126 141 I3S

77 S9 S6 27 16 3 5 3 2 2 0 0 0 0 0

0 0 0 0 0 1 2

Observed Mean TL (SE)

322 383 476 592 695 779 828 896 942 981

1024 1043 1079 1079 1092 1088 1091 1089 1130

mdash 1060 1140

322 383 476 593 695 778 824 896 937raquo 976 989raquo

1023 1096 1054 1110 1086 1081

mdash _ mdash mdash mdash

mdash mdash mdash mdash mdash

992 1085

(16) (17) (15) (9) (8) (7) (8) (8) (9) (7) (10) (18) (9) (6) (15) (15) (20) (2)

(-) (21)

(-)

(16) (17) (15) (9) (8) (7) (7) (9) (9) (8) (13) (31) (7) (12) (20) (38) (47)

(-) (25)

Mm TL

283 257 350 443 487 467 654 676 802 765 890 642

1030 1029 1010 1008 1035 1086

mdash _

1039

-

283 257 350 443 487 467 6S4 676 802 765 890 642

1085 1029 1082 1048 1035

mdash

mdash _ mdash

mdash mdash mdash mdash mdash _

1060

Max TL

361 530 678 785 910 992

1110 1041 1067 1085 1129 1170 1125 1123 1777 1127 1165 1089

mdash _

1080

-

361 530 678 785 910 980

1020 1040 1065 1085 1085 1 170 1110 1100 1150 1124 1128

_ _ _ mdash

mdash mdash mdash mdash mdash

1110

Predicted TL

281 420 538 637 722 793 854 905 949 986

1017 1044 1066 1085 1101 1115 1126 1136 1144 1151 1157

HOOD AND SCHUEDER GAG UFE HISTORY

Table 3 Continued

345

-vislSMSafei

Aie

vn vin IX X XI

xn XIII XIV XV XVI XVII

XIX

N

1 4

13 21 14

9 12 10 7 4 3 1 0 2 1

Observed Mean TL (SE)

946 1019 1002 1070 1068 1075 1089 1088 1088 1096 1089 1130

mdash 1059 1140

(-) (22) (17) (7) (13) (12) (6) (18) (17) (24) (2) (-)

(21) -)

M i n T L

971 865

1018 998

1030 1050 1010 1008 1059

M a i T L

1067 1085 1129 1150 1125 1123 1222 1127 1165

bulldeg-laquoideg_^ mdash

W^m ^^S^9

mdash ^ ^ ^ 1 ^ ^ ^ ^ ^ ^ P

Predicted TL

llwilUKti

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